While conducting radiation therapy of a patient tumor (target zone, or target organ) accurate location of the tumor is necessary. For location in a 3-dimensional space, a physician or radiologist at first scans and acquires, in a Computed Tomography (CT) room, a CT image data set of the patient then reconstructs, via a geometric computational algorithm, a corresponding 3-dimensional graphic image of the patient. The patient tumor can now be located by its 3-dimensional coordinates. Next, the physician or radiologist moves the patient into an accelerator room and recovers the tumor location by positioning an isocenter of the accelerator so that it accurately coincides with the 3-dimensional coordinates of the patient tumor. Finally, the radiation therapy commences. At present, the accelerator of radiation therapy equipment can only rotate around a horizontal axis generally parallel to the patient body (the Z-axis). In addition, radiation beams emanated from the accelerator are also constrained to a plane perpendicular to the Z-axis lacking the freedom of choosing their radiation incident angle. Consequently, such constraints of the present-day radiation therapy equipment impose substantial functional limitations to the diagnosis and directional radiation treatment of diseases.
Targeting the above-described constraints, a corresponding set of solutions have been proposed. The solutions include hanging the accelerator upon a sliding track that is parallel to the Z-axis for a reciprocating sliding movement along the Z-axis plus a pendulum-like movement of the accelerator head in a YZ-plane (Y-axis being vertical) whereby realizing a radiation with 3-dimensional multi-incident angle. However, firstly the heavy weight of the accelerator causes the accelerator-hanging mechanism and its associated driving mechanism to become highly complex with high production cost. Secondly, the pendulum-like movement of the accelerator head can cause instability of the radiation beams. Thirdly, the tight coupling between the accelerator and its driving mechanism can cause interference to the whole treatment system further increasing production difficulty and cost. Fourthly, it is noted that the treatment system has an integral digital image detection planar board that functions to detect radiation from the accelerator and to render its radiation image. Thus, the pendulum-like movement of the accelerator head would cause a loss of real-time functional synchrony between the accelerator and the digital image detection planar board, affecting the ability of the treatment system to perform treatment with real-time diagnosis and compensation.
To solve the above described problems, the present invention proposes a 4-dimensional (three-dimensional space+time) positioning radiation therapy apparatus that, through tracking in a 4-dimensional space, allows the administered radiation dosage to vary dynamically according to the space-time trajectory of the target organ to realize accurate treatment with simple, easy to manufacture structure while simultaneously shortening treatment time and saving cost.